External fixation and foot-supporting device

Abstract

In one preferred embodiment according to the present invention, an external fixation device for the foot and ankle of the human anatomical skeleton includes a yoke, three adjusters, and a base (or foot plate). The foot plate selectively couples to the yoke without the need of any tools, thereby enabling the patient to self attach and remove the foot plate from an existing circular fixation structure.

Description

PRIORITY CLAIM[0001]The present application claims benefit under 35 USC Section 119(e) of U.S. Provisional Patent Application Ser. No. 61 / 049,865 filed on 2 May 2009. The present application is based on and claims priority from this application, the disclosure of which is hereby expressly incorporated herein by reference.BACKGROUND[0002]The present invention relates to therapeutic orthopedic devices for fixating, immobilizing, and manipulating the human anatomical skeleton, particularly the foot and lower leg. And, more specifically, the present invention relates to external frame systems and devices for fixating lower leg bones and the foot with respect to the tibia.[0003]External Fixation devices locate segments of bone relative to a reference location of the skeleton for varied purposes including reconstruction of fractured or deformed extremities. By distracting or compressing portions of the anatomical skeleton, external fixation devices can correct angulation, rotation, and tr...

AI Technical Summary

Benefits of technology

[0025]The present invention overcomes the problems of the current state-of-the-art in external fixation systems. In a preferred embodiment, the present invention provides an external fixation system that improves patient comfort, enables a more normalized gait, encourages good hygiene, and provides ease of removal. Further, a preferred embodiment of the present invention provides mechanical features that enable self adjustability by the patient, provide a flexing suspension to absorb shock during gait, enable a more normalized gait, reduces complexity, is more economical to produce, and reduces the number of components compared to contemporary systems.

[0026]In one preferred embodiment, the present invention includes a system and device for external fixation of the anatomical skeleton, particularly as it relates to the lower leg, ankle, and foot. In this embodiment, patients undergoing ring external fixation treatment of foot and ankle problems have increased ambulation and function over any known or current systems and devices. The device of this embodiment is specifically made to attach to a (155 mm) Taylor Spatial Frame brand foot ring available from Smith & Nephew, Memphis, Tenn., USA, for patients undergoing treatment of pathology of the lower extremity requiring fixation of their foot in the ring external fixator. The device of the present invention fully adjusts allowing patients to ambulate with as normal a gait as possible with the ring fixator in place. The device's adjustability allows for deformity of the foot and ankle as well as non-plantigrade mounting of a foot ring, which may occur with foot ring applications. The device includes quick connect and release mechanisms that allow patients to self remove the walking portion of the device.

[0027]In one preferred embodiment, the system of the present invention includes an external ring fixation device consisting of three clamps commonly applied to the walking portion consists of an aluminum plate with a rubberized, surface-contacting sole or, alternatively, a rocker-sole addition. The plate is connected to the three specialized clamps via adjusters, a unique assembly consisting of an adjustable rod (or strut) and ball-and-socket joints. This allows adjustability, stability, and strength.

Problems solved by technology

One drawback of circular fixation treatments includes a lengthy treatment duration—often in excess of one year—during which the patient's foot and lower leg are immobilized in a cumbersome external fixation structure consisting of varied components including pins, wires, support rods, clamps, and frames.

Another drawback of existing circular fixation treatments and systems is that patients have restricted movement.

This restriction is a result of the quantity and placement of cumbersome components that—due to their size, weight, and anatomic placement—severely restrict and impair motion to a range that is far less than the patient's accustomed normal range.

However, existing circular external fixation systems inadequately address the patient's desire and need to use the constricted limb as close to normal as possible.

Specifically, existing external fixation systems inadequately address the patient's need for an ambulatory load-bearing construct that enables or approximates the patient's normal (unencumbered) gait.

Although these solutions provide a “contact” platform under the foot, they fail to provide adequate cushioning, adjustability [for gait], and removability, or any combination of these characteristics.

And, more problematic, injuries and other abnormities of the foot require additional frame elements including a foot ring.

Foot rings can be difficult to align and mount either because of more challenging deformities of the foot such as equinus contractures or varus deformities, or simply because of the difficulty surgeons encounter when trying to manually align the foot ring properly with the foot.

Often the result is an attached foot ring that is non-plantigrade, or poorly aligned with the horizontal axis of the foot.

As a result, the patient often cannot load-bear due to hardware attachments beneath the foot ring, the position of the foot ring, the position of the foot ring relative to the foot, or because of a pre-existing anatomic position that prohibits them from walking normally.

Additionally, many prior-art foot rings, or foot-ring walking attachments, do not provide any cushioning or traction-enhancing features.

Known prior-art or state-of-the-art external fixations systems present additional drawbacks when applied for use as a walking attachment.

Frame members that were not designed specifically as a footplate do not provide for the cushion or tread necessary for such a longitudinal course of treatment.

Moreover, these devices are difficult to adjust to a patient's comfort given the planar variances of each patient's foot position and the need for the device to adapt to a wide spectrum of variation between individual patients.

Further, because the adjustments made to existing devices require tools (such as wrenches), to tighten and loosen nuts on threaded rods and on bolts, it can be very difficult, if not impossible for a patient to accurately adjust their ring for comfort or hygiene.

Any comfort gain by removal for bathing or at bedtime is eclipsed by the arduousness of this task and, often for the entire duration of treatment, an individual patient will not remove their load-bearing ring.

This additional length causes an abnormal gait and further causes hip and knee problems.

The deficiency of this device is multifold in that it nearly eliminates all available attachment points for wire fixation to the foot ring due to it's size and shape that mirrors the foot ring and, hence eclipses, all attachment point options.

The DePuy device, because it attaches using multiple bolts and nuts, makes very difficult if not impossible for the patient to remove his device when bathing or sleeping.

Finally, and most significantly, the DePuy device does not inherently provide a means for planar adjustability; there is no available means for either a surgeon or patient to easily adjust the position of their means for comfort, supplemental correction, or just ambulating.

Problems common to the current-state-of-the-art devices, represented above, include an unacceptable level of precision that must be maintained during the creation of the frame structure in orientating each component while a multitude of fasteners are tightened.

Not only is such adjustments time-consuming, they are often impossible for the patient to make on their own because the patient is unable to reach the fasteners due to poor flexibility or simply because the location is out of the range of normal-human motion for a device worn on the foot.

Moreover, the inter-dependent nature of the fasteners often require incremental adjustments made in sequence with each of the multiple fasteners, which requires a skill beyond the average patient.

Despite the varied attempts at improving external frame fixation systems, many problems specific to the lower extremity and, particularly, to the foot, have not been adequately addressed.

For example, patient comfort, gait, hygiene, ease of removal are inferior in known systems.

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